Arcane Blackout

You unleash a magic surge that makes anyone in its radius (including you) lose the ability to cast spells, concentrate on spells, or benefit from magic for the spells duration if they fail a constitution saving throw.

For every 10 creatures caught within the spell, a wild magic surge happens in the area.

When cast using a 7th-level or higher slot, the radius increases by 20 feet per slot level above 6th.